FILTER, DUPLEXER AND COMMUNICATION APPARATUS

摘要

PURPOSE: A filter, a duplexer and a communications device are provided to miniaturize a duplexer by including a film bulk acoustic resonator or a filter in a duplexer. CONSTITUTION: A film bulk acoustic resonator comprises a substrate, a bottom electrode(2), a piezoelectric-foil and an upper electrode(4). The bottom electrode is formed on the substrate. The piezoelectric-foil is formed on the substrate and the bottom electrode. The upper electrode is formed on the piezoelectric-foil. The upper electrode includes a part facing the bottom electrode. The shape of an electrode region overlapped between the upper electrode and the bottom electrode has facing unparallel outer sides. One outer side among the outer sides is faced with the electrode region of adjacent other film bulk acoustic resonator. An interval between the one outer side and the outer side facing the one outer side is constant.